An '03 with those miles shouldn't be burning any oil between oil/filter changes.
Never mind the manufacturers bs considering 1 quart in 1k mlies 'normal'. I think that's nonsense. JMO.
I own a 2000 Olds Silhouette 3.4L 123k miles) (sister to your Montana) and my daughter has an '03 Montana (87k miles) like yours and neither one burn oil between oil/filter changes. Both have changes done at 3mo/3k mile intervals (mostly in town driving).
However, if it were mine, I'd have a cylinder compression test done to ensure no unseen problems, even if only for peace of mind.
You MAY have a small leak that only occurs while the engine is hot and may not be being routed to anything hot to produce a smell.
Have a good engine/compartment detailing/cleaning done, then very closely check all gaskets for tiny leaks.
One minuscule slip-up when manufacturing the engine can result in using/burning up oil.
In the meantime, just keep driving the van and check the oil level (engine cold) periodically.